Various printing methods are used in printing machines. Non-impact printing methods (NIP) are understood to be printing methods that do not require a fixed, i.e., physically invariable, printing forme. Such printing methods produce different print images in each printing operation. Examples of non-impact printing methods include ionographic methods, magnetographic methods, thermographic methods, electrophotography, laser printing and in particular inkjet printing methods. Such printing methods usually have at least one image-generating device, for example, at least one print head. In the case of the inkjet printing method, such a print head is embodied as an inkjet print head, for example, and has at least one nozzle, preferably a plurality of nozzles, by means of which at least one printing fluid in the form of ink droplets, for example, can be transferred to a printing substrate in a targeted manner. The printing substrate should preferably be at the most constant possible distance from the image-generating device, in order to be able to coordinate the generation of images in time while at the same time avoiding damage to the image-generating device.
In inkjet printing methods, in particular in conjunction with water-based ink, for example, it may happen that the printing substrate becomes deformed, forming ripples, for example. Such ripples may entail the risk of damage to both print heads and the printing substrate, on the one hand, while resulting in a low print quality, on the other hand, due to different printing fluid droplet flight times, for example.
DE 10 2013 208754 A1 discloses a printing assembly having movable print heads.
GB 2 357 996 A discloses a suctioning of air in conjunction with inkjet printing.
US 2012/0 007 916 A1 discloses a printing assembly, in which suction boxes, each extending over the total working width of the printing assembly, are arranged. Each suction box has a fan blowing air to the outside.
US 2014/0 240 397 A1 discloses a printing assembly having suction boxes, in each of which spacers are arranged to reduce the flow cross section and to increase the velocity of flow, so that condensed solvent cannot collect in vertically extending sections and drop back downward.
JP 2012-000 932 A discloses a printing assembly having a plurality of suction boxes, which together extend over the working width of the printing assembly.
JP 2013-111 954 A discloses a printing assembly having a suction box with internal separation devices, which ultimately open into a single outlet of the suction box.
US 2009/0 122 107 A1 discloses a printing assembly having a plurality of print heads arranged one after the other in the direction of transport, wherein multiple crossbars are arranged, one after the other, in the direction of transport, extending between the side walls of a frame.
US 2009/0 244 124 A1 discloses a printing assembly having a framework and a frame pivotable thereto, to which print heads are attached by means of adjusting devices, and which has an alignment device for print heads, wherein an operating element may optionally be used for this, to influence alignment units arranged upstream of this operating element or downstream of this operating element with respect to a direction of transport. The print heads are arranged on a plurality of crossbars arranged one after the other.
DE 603 05 366 T2 discloses dryers, wherein interspaces, in which print heads are arranged, are themselves arranged between these dryers as seen in the direction of transport.
US 2011/0 043 554 A1 discloses a printing assembly having a frame with two side walls, between which a transport path for printing substrate runs at least partially, and having at least two crossbars, each extending from one side wall to the other side wall.
JP 2010-5 850 A discloses a printing assembly having a cleaning and covering device for print heads, wherein this device can be arranged temporarily between print heads in the direction of transport.
U.S. Pat. No. 6,419,334 B1 discloses a supporting body, which supports print heads and can be supported from above on journals of a frame. A precise position is ensured by three journals.
DE 10 2010 060 406 A1 discloses a printing assembly having supporting bodies, on which print heads are arranged and which can be retracted vertically upward relative to a frame of the printing assembly.
DE 10 2010 037 829 A1 discloses a printing assembly, in which print heads are arranged on crossbars and are movable vertically and/or in a transverse direction together with the crossbars to bring them into contact with closure devices.
US 2003/0 039 499 A1 discloses a device, with which print heads are moved on crossbars orthogonally to a transport direction for the printing substrate during a printing operation. For this purpose, the print heads are arranged on a suitably movable supporting body, which is therefore suitably short in the transverse direction.
US 2014/0176369A1 discloses a printing assembly in which suction openings are explicitly arranged only in limited regions.
EP 1 787 816 A2 discloses a printing assembly having two suction boxes and a first suction box is arranged along a transport path between print heads and also serves to convey air beneath a downstream print head. A second suction box serves to remove air downstream of the last print head.
EP 2 357 086 A1 discloses a printing assembly having suction boxes.
JP 2004 276 381 A discloses a printing assembly having devices for cleaning print heads. These devices are arranged opposite the print heads and having suction devices whose openings are coordinated with the print heads with respect to size and face upward. Lateral shields ensure that air and ink mist can also be removed by suction when a printing substrate is located between the print heads and the suction devices.